The Marketplace is where DGC sells items and services for real money. The currency used is Daybreak Cash (DC). 100 DC is equivalent to US$1.00. Daybreak Cash used to be called Station Cash (SC) when the company was Sony Online Entertainment.
All Access accounts are granted 500 DC per month. The granted DC must be claimed each month. To claim it, open up the Marketplace on any character on the account. The upper left corner of the Marketplace window has the All Access DC reward button. You cannot claim your monthly DC if your DC total would be more than 50,000 after the claim. You would need to spend some first.